The invention is based on a device for mounting an electric motor, in particular a fan motor, according to the preamble of the independent claim.
Fan motors for heater and air-conditioner fan systems that are used in motor vehicles, for example, are usually decoupled from the vehicle in terms of vibration engineering in order to reduce a transfer of structure-borne noise from the motor and/or the fan unit to the vehicle body and, therefore, into the passenger compartment of the vehicle.
Main sources of undesired vibrations, e.g., in DC motors, are imbalances in the motor and the commutation inside the motor. Commutation occurs when the copper windings of the armature conduct current while the motor is operating. During each rotation of the armature shaft, current flows through the windings in the motor once in each direction. The current flow in the windings, influenced by a permanent magnet field, produces a reaction that is transferred as a torque pulse.
Common methods for mounting motors of this type in fan housings involve mounting the motor first in an adapter part, e.g., by plugging it in, and then mounting said adapter part in a motor holder. A flange is typically located on the motor holder itself to securely join the motor with the air conditioner, e.g., via a carrier part formed on the vehicle body.
To mount the actual motor in the adapter part or a motor housing, it is known to use snap-in hooks, to screw the components together, and to clamp the motor between two housing halves. It is furthermore known that electric motors can be pressed, with their pole rings, directly into a motor holder.
Elastic damping elements can be inserted between the adapter part accommodating the motor and the motor holder itself, which said elastic damping elements are intended to ensure that the motor holder is decoupled from the motor vibrations.
Normally, rubber is inserted in the form of appropriately formed rubber elements between the motor and the motor housing, in the flange or between the flange and a carrier element of the air conditioner, in order to dampen oscillations forming in the air conditioner or the vehicle body, and to suppress noises that are bothersome to the driver or his passenger in the passenger compartment of the vehicle.
In practical use, there are numerous possibilities for inserting the rubber and/or decoupling elements composed of rubber between the housing flange and the air conditioner and/or between the motor and the motor housing, in order to dampen the vibration pulses.
For example, DE 43 34 124 A1 discloses a device for housing an electric motor that attains a particularly low-vibration and, therefore, noise-damping effect by the fact that at least one elastic damping element is located between the inner walls of this housing device and the outer walls of the motor housing facing them, which said damping element bears against the walls of the housing device and the motor housing that face each other.
These elastic damping elements, which are rubber elements formed appropriately in a preferred exemplary embodiment of the device disclosed in DE 43 34 124 A1, require higher assembly and material expense, which unnecessarily increases the costs of such a device.
A holder for an electric motor is described in DE 36 18 177 A1, in the case of which the motor is inserted in a motor holder and secured against axial displacement by means of inwardly projecting, resilient noses.
A silenced holding device for an electric motor is made known in DE 196 52 328 C2, in the case of which the electric motor is placed in a first plug-in receptacle, which functions as an adapter part, and is secured axially by means of snap-in hooks. This plug-in receptacle comprises radially displaceable tongues in the fashion of flat springs distributed around its outer circumference. Pegs that project radially outwardly are integrally molded on these tongues, onto which correspondingly-shaped, silencing intermediate parts can be attached, such as rubber caps with a clamped connection.
The adapter part is inserted into a larger motor holding part during assembly of the holder disclosed in DE 196 52 328 C2. If the electric motor is now inserted, with its housing, into the adapter part, the tongue-like flat springs are pressed outwardly, so that they—helped along by the silencing intermediate parts—latch into corresponding immobilization openings of the motor holding part.
The method for holding the motor as disclosed by the teaching of DE 196 52 328 C2 is extremely costly and component-intensive, which results in higher assembly expense and, therefore, cost and time expense.